This puzzle wasn't very hard. It was probably more on the contemporary side of general knowledge than anything obscure. Only 1dn might be for the older folk. I have one I haven't quite parsed but maybe by the time I get to write it up . . .

ACROSS
1) PISTACHIO : h(Cats)ip<,i,o : surface is a bit scatty.
6) PAVED : p----d <> Ave : 'tunnels' being a containment indicator.
9) TOR : ---tor : ie orator minus 'or' and 'a'.
10) TRAILBLAZER : trail,blazer
11) ON TARGET : (rent,got,a)*
12) AVOWED : --av--,owed
15) KOHLS : hm(Coles) : learnt this one from my teenage daughter just the other week. Think Egyptian eyes.
17) WHODUNITS : wits <> (hound)* : a great word for setters as it's unusual and even with W_O_U_I_S it seemed a mistake more likely.
18) SKI PATROL : skip,a,trol- : 'vile Shorten poster' is not good. 'Shorten vile poster' works but obviously not surface-wise. So DA should've tried again.
19) TUTSI : tuts,--i--
21) I ROBOT : -iro bot---- : I think the 'de' is meant to be the 'hidden' indicator, ie French 'of'. The idea is clever. Not everyone will like it.
22) IMPOTENT : imp,o(xygen)tent : this was the unparsed one. You have to know that IC is Intensive Care, then deduce that otent is O-tent which is a contraction (of DA's) of oxygen tent. It's definitely one to be solved in retrospect. The idea was okay but was stretched too far to be fair.
25) STAR BILLING : st(if/Libra<)ling : Libra backwards replaces if in stifling.
27) TIM : -t-i-m
28) ROLEX : ---rol ex----
29) GREAT APES : hm(grey,tapes) : 'recorded' is one thing but playing the recording is where one hears it.